CRYSTALLOGRAPHY OF THE HEMOGLOBINS OF AVES. 163 



Habit prismatic by development of the two pinacoids (100) and (010) in the zone 

 of c; the termination is oblique and is produced by the clinodome (Oil), text figures 33 

 and 34, usually only one end of the crystal being seen. 



Pleochroism rather strong; a pale yellowish, b deep red, c deep red. Extinction 

 on (100) is straight; on (010) it is oblique with the angle c A <! = 11. Orientation of the 

 elasticity axes is hence a A a = 14i, CA (5 = 11, b=6. The plane of the optic axes is the 

 plane of symmetry, and from the character of the double refraction 6 is nearly equal 

 to c; the acute bisectrix Bx a = a, hence the optical character is negative. 



GOOSE, Anser anser. Plate 9. 



Blood of the domestic goose was obtained by killing and bleeding 

 the bird. Repeated attempts were made to crystallize it. Finally, after 

 repeatedly freezing and thawing the blood, and then centrifugalizing and 

 adding ether, and (in preparing the slides) allowing the drop to become very 

 concentrated before covering, crystals were obtained by keeping the slides 

 for several hours at about the freezing-point. On bringing the prepara- 

 tions into a warm room the crystals dissolve readily, and all examinations 

 were made and photographing done at a room temperature of about C. 

 The crystals were normal oxyhemoglobin. 



Oxyhemoglobin of Anser anser. 



Tetragonal or pseudo-tetragonal : No axial ratio could be determined, as no pyram- 

 idal planes were developed. 



Forms observed: Prism (110) and base (001). 



Angles: 110 A lTO = 90; 110 A 001 =90. 



Habit thick tabular, the thickness one-third to one-fourth of the width of the plate 

 (text figure 35) ; some also quite thin. The plates grow in clusters, as though twinned 

 on a pyramid (101), also in irregular aggregates; sometimes 

 arborescent by the overlapping of the plates and extension 

 along a crystal axis. Smaller crystals, developing later than 

 the normal plates, are nearly equidimensional and closely 

 resemble cubes. 



Pleochroism was not noticeable in most cases, perhaps J~ 



due to the very deep color of the plasma; some large thick FlG 35 . Anser mser Oxy hemo- 

 crystals showed a slight pleochroism. On the basal pinacoid giobin. 



the crystals are singly refracting when examined in parallel 



polarized light; in convergent light, the uniaxial interference figure is seen as a very 

 dusky cross. Examined on edge, the vertical axis (the extraordinary ray) was seen to 

 be the direction of less elasticity ; hence s > w and the optical character is positive. 



When examined on edge, the crystals polarized as a whole and did not indicate 

 any appearance of twinning, but from the fact that similar tetragonal characters are 

 produced by what appears to be homogeneous regular growth in the case of the whistling- 

 swan blood Olor columbianus which is distinctly orthorhombic, it is quite possible 

 that these blood crystals are only pseudo-tetragonal. 



TRUMPETER SWAN, Olor buccinator. Plates 9 and 10. 



This specimen of blood was received from the Philadelphia Zoological 

 Gardens. The blood was oxalated, ether-laked, and centrifugalized, and 

 preparations made as usual. The slides were kept at a temperature near 

 the freezing-point, but no crystals developed until after 24 hours. Even 

 then only scattered crystals appeared, excepting in two slides. The crystals 



